1. Field of the Invention
This invention relates generally to a method of obtaining a lung biopsy sample using minimally invasive methods. More particularly, the invention relates to a method of obtaining a lung biopsy sample percutaneously with a reduced risk of pneumothorax. Still more particularly, the invention relates to an apparatus and method for obtaining a lung biopsy sample and reliably sealing the entry path into the lung to reduce the risk of pneumothorax. Still more particularly the invention relates to an apparatus and method for obtaining a lung biopsy sample and sealing the entry path into the lung via the delivery of thermal energy to a target tissue site or use of a polymer sealant or mechanical closure device.
2. Description of the Related Art
The lungs are the organs for respiration in mammals. They have a set of unique material properties adapted to this function including elasticity, porosity and a large amount of surface area for gaseous exchange to efficiently oxygenate and remove waste gases from the blood. In the adult human, each lung is 25 to 30 cm (10 to 12 in) long and roughly conical. The left lung is divided into two sections or lobes: the superior and the inferior. The right lung is somewhat larger than the left lung and is divided into three lobes: the superior, middle, and inferior. These lobes are divided by the oblique and horizontal fissures. The left lung only has two lobes, an upper and lower. These lobes are divided by the oblique fissure. Both lungs are further divided by bronchopulmonary segments.
The two lungs are separated by a structure called the mediastinum, which contains the heart, trachea, esophagus, and blood vessels. Both right and left lungs are covered by an external membrane called the pleura. The outer layer of the pleura forms the lining of the chest cavity. The inner pleura covers each lung. A vacuum is maintained between these membranes that causes the lungs to expand during inhalation as the diaphragm muscle is pulled down causing the chest cavity to expand.
While the structure of the lung is extremely well suited as a respiratory organ at the same time it makes them susceptible to damage and disease from environmental factors by trapping disease causing pollutants within the structure of the lung. Due to the spread of western industrialized society, factors such as increasing concentrations of air pollution and incidents of smoking are resulting in a worldwide increase in the incidence of lung disease. Smokers and people who live in cities are exposed to substantial levels of carcinogenic air pollutants such as benzene and polycyclic aromatic hydrocarbons (PAHs). Two of the more prevalent disease resulting from these and other risk factors include emphysema and lung cancer. Lung cancer is a particularly insidious and deadly lung disease and each year it kills more Americans than any other type of cancer.
A key factor in the prevention and successful treatment of lung disease is early detection. One of the best tools available to the physician in this regard is the taking of a lung tissue sample or lung biopsy. In fact, biopsy is often necessary or otherwise highly advantageous as an adjunct to other diagnostic methods to improve diagnostic accuracy. Efforts to biopsy the lung have focused on three key requirements: 1) The need to harvest adequate tissue from an organ that is mostly air; 2) the need to obtain a biopsy specimen from within the lung tissue without permitting air to leak either from the outside or from the lung into the pleural space; and 3) the need to have access to the entire volume of the lung. The two currently practiced methods for lung biopsy: transbronchial biopsy and percutaneous biopsy have not been able to adequately address all three needs. In fact, both methods have significant clinical issues and technical drawbacks.
In particular, both methods present the risk of a potentially lifethreatening complication known as pneumothorax due to puncture of the lung by the biopsy needle. A pneumothorax is a collapse of the lung that occurs when the airtight integrity of the lining of the chest cavity (the pleural membrane) is broken due to a penetrating injury or a complication of a lung disease. This causes air to enter and collect in the pleural cavity (which is normally in a partial state of vacuum), collapsing the lung and severely, if not totally, impairing its function. The risk of this complication is considerable, potentially life-threatening and requires immediate medical intervention including surgery to vent air from the chest cavity. A recent ten year study has shown that the risk of pneumothorax for both fine needle biopsy and percutaneous biopsy is 11.7% (Greif J, et al. Percutaneous core needle biopsy vs. fine needle aspiration in diagnosing benign lung lesions Acta Cytol 1999 September-October; 43(5):756-60).
During the procedure of transbronchial biopsy a flexible fiberoptic bronchoscope is employed as a conduit through which a biopsy instrument is passed from the outside of the patient through the airways of the lung into the lung tissue. The use of fiberoptic devices for collecting tissue samples is done as part of a procedure known as fiberscopic-bronchoscopy which is a visual examination of the bronchial tubes. The bronchoscope, which is inserted down the trachea and into the bronchial tubes, has lighting and magnifying devices that enable the physician to see the bronchial surface. During this procedure the physician can obtain samples of cells for later microscopic examination. However, accessing the lung tissue biopsy site via the throat has the drawbacks of requiring that the patient be intubated (a sometimes difficult and time-consuming process) and put under general anesthesia (which increases mortality and morbidity). These and other factors result in the procedure taking considerable time, one to two hours, and burdening the patient with considerable expense due to required personal, equipment and facilities. Also due to size limitations, the distal end of many bronchoscopes, particularly rigid bronchoscopes, cannot be passed any further than the beginning of the segmental bronchi of the lower lobes of the lung. Thus, inaccessibility of significant portions of the lung is another key limitation of transbronchial procedures. Further, the procedure can result in air entering into the pleural space causing partial or complete pneumothorax.
Percutaneous needle biopsy involves introducing a biopsy needle (known as a transthoracic needle) through the chest wall usually after making a small skin incision. This procedure is often necessary, as many areas of the lung are too inaccessible to bronchoscopy, particularly areas abutting the chest wall. However, while the procedure provides increased accessibility and shorter procedure times versus transbronchial procedures, it has significant clinical risks and limited diagnostic accuracy. These risks include pneumothorax, and vessel perforation causing embolism and/or uncontrollable hemorrhage. Pneumothorax in percutaneous biopsy can result from either lung perforation or accidental suction of air into the chest during stylet changes. Pneumothorax is a likely event in percutaneous biopsy due to the sizable injury of the pleural membrane frequently resulting from this procedure.
Depending upon the patient, these risks may be so great that invasive surgical procedures such as open lung biopsy are preferred and/or are the only option. This is the case for patients who are receiving anticoagulants such as coumadin, making them particularly susceptible to uncontrollable pulmonary hemorrhage from inadvertent vessel perforation or other trauma by the biopsy needle. Further, percutaneous biopsy only has a 40-50% sensitivity in the diagnosis of malignant disease; a critical shortcoming.
There are two approaches to percutaneous needle biopsy: core biopsy and needle aspiration. In core biopsy the needle is advanced into tissue for obtaining a core or plug of tissue sample within the interior of the needle which is subsequently withdrawn. In needle aspiration tissue is obtained by inserting the needle to the desired tissue site and applying a vacuum to suck cells and tissue through the needle and outside the body. Each of these procedures has its respective tradeoffs and limitations. However, both still present a significant risk of pneumothorax, particularly with increasing needle path length through the lung (R. Erlemann: xe2x80x9cPunch biopsy or fine needle aspiration biopsy in percutaneous lung puncture.xe2x80x9d Radiologe. 1998 February;38(2):126-34.).
While the core biopsy approach has been able to obtain larger tissue samples that provide increased diagnostic accuracy and sensitivity verses fine needle aspiration, it has the disadvantage of a higher incidence of complications including pneumothorax. This is in part due to the fact that currently available core biopsy needles (e.g. Silverman, Cope and Abrams) are likely to cause sizable injury to the pleural surface of the lung, a condition which promotes pneumothorax. Specifically, the rigidity of such needles against the lung tissue results in tearing or stretching of the tissue at the point of entry, such that leakage may occur while the needle is in place. Further, these needles do not include an air seal, resulting in an increased chance of air being introduced from outside the body (through the needle) also causing the lung to collapse and or an air embolism (discussed herein).
Also, larger diameter biopsy needles such as those used in core biopsy have an increased risk of puncturing a pulmonary vessel resulting in uncontrollable bleeding. The risk of vessel perforation results from the fact that the physician is at times without visualization from flouroscopy or a viewing device being effectively blind as to the position of the biopsy needle within the lung. Once a vessel is punctured, uncontrollable bleeding can quickly result as an well as air embolism. The extent of vessel damage and resultant bleeding is related to the diameter of the biopsy needle and the shape of the tip.
Air embolism is another complication of percutaneous lung biopsy. Embolism occurs when the needle enters a vessel in the lung and when the biopsy needle or stylet is removed to apply negative suction. Air sucked into the vessel in this manner may markedly decrease the pressure in the vessel. When air gets into the vessel it travels to vital organs and blocks the blood supply and the patient can die as a result.
Currently, the only satisfactory percutaneous lung biopsy procedure from a safety standpoint is the xe2x80x9cSkinny Needlexe2x80x9d technique. In this procedure a needle, similar to a standard intravenous needle (18 to 21 gauge) but somewhat longer and having an angled sharp cutting tip, is attached to a syringe. The needle is inserted into the lung through the chest wall and a vacuum is applied to the syringe whereby lung cells are sucked into the needle. The needle is then withdrawn from the chest and the cells forced from the needle onto a microscope slide for examination. This technique is simple since it can be performed at the patient""s bedside; quickly, 15 to 30 minutes, and inexpensively. Since the needle is of narrow bore and has a sharp cutting tip, the injury to the pleural surface is minimal. This, together with the needle being air-sealed by the syringe, results in a lower incidence of lung collapse versus other percutaneous techniques. However the xe2x80x9cSkinny Needlexe2x80x9d device and technique have a limitation that makes it the least satisfactory of all lung biopsy techniques, that is the relative paucity of tissue obtained due to the structure of the lung being predominantly air. This is a critical shortcoming in that larger tissue sample sizes are preferred or necessary particularly for histological tissue examination since certain diseases can not be diagnosed by other methods (e.g. cytologically). In many instances, the larger tissue sample sizes required by histological examination has required open lung biopsy procedures.
Thus, the currently available percutaneous lung biopsy needles face a design trade off in terms off efficacy versus safety. They need to strike a balance between needle diameter, flexibility and stiffness to minimize the chance pneumothorax and improve the sample size. Unfortunately, none have succeeded and all have had to comprise safety or diagnostic accuracy to some extent. Additionally none of the currently available lung biopsy needles address various contraindications in doing a biopsy. These include: (i) absence of sufficient pleural fluid, making it difficult to recognize the plane of cleavage of visceral and parietal pleura resulting in a high likelihood of lung perforation/pneumothorax; (ii) empyema; (iii) uremia; (iv) use of mechanical ventilation devices; hemothorax, which is accidental injury to the neurovascular bundle; resulting from misdirection of the biopsy hook upward along the inferior margin of the rib; and (v) coagulation defect, resulting in a likelihood of pleural bleeding.
Clearly, there is a need for a lung biopsy device and procedure that is able to satisfy previously unmet safety and efficacy requirements. These include being able to obtain a sufficient biopsy tissue sample to make reliable diagnosis from an organ that is mostly air without causing pneumothorax, embolism, hemorrhage, pleural trauma or other injury or adverse complication. There is also a need for a device and procedure that allows the physician to monitor for air leakage into the lung and pleural space to prevent pneumothorax before it happens. There is also a need for a device and procedure that allows the physician to reliably seal tears within the pulmonary and pleural tissue to prevent pneumothorax or plumonary hemorrhage. There is a further need for a device that can be precisely positioned in a target tissue zone. Yet another need exists for a lung treatment apparatus that can controllably and completely ablate a lung selectable lung tissue volume.
An embodiment of a lung treatment apparatus includes an elongated member having a proximal portion, a distal portion and a lumen. The distal portion includes a tissue piercing distal end having at least one of a flexibility, a lubricity or a shape configured to minimize injury to a pleural membrane. An energy delivery device is coupled to the distal portion of the elongated member. The energy delivery device has a shape configured to deliver energy to a target lung tissue volume including sufficient energy to close a void space within or adjacent the tissue volume. The energy delivery device is further configured to be coupled to a power source. At least one aperture is coupled to one of the elongated member or the energy delivery device. A sensor is coupled to the elongated member.
In another embodiment, a lung treatment apparatus includes an elongated member having a proximal portion, a distal portion, a lumen and at least one aperture coupled to the lumen. The distal portion includes a tissue piercing distal end configured to minimize injury to a pleural membrane. An energy delivery device is coupled to the distal end of the elongated member. The energy delivery device has a shape configured to deliver energy to a target lung tissue volume. The energy delivery device is further configured to be coupled to a power source. A closure device is coupled to the elongated member. The closure device is configured to substantially close a tissue void space within the lung.
In yet another embodiment, a lung treatment apparatus has an energy delivery device that includes a first RF electrode with a tissue piercing distal portion and a second RF electrode with a tissue piercing distal portion. The first and second RF electrodes are positionable in the introducer as the introducer is advanced through tissue and deployable with curvature from the introducer at a selected tissue site. A groundpad electrode is coupled to the first and second RF electrodes. A first sensor is coupled to the groundpad electrode.
In another embodiment, a method of ablating a selected pulmonary tissue mass is provided utilizing a multiple antenna device with feedback control. The multiple antenna device can be an RF antenna, a microwave antenna, a short wave antenna and the like. At least two secondary antennas can be included and laterally deployed from the primary antenna. The secondary antenna is retractable into the primary antenna, permitting repositioning of the primary antenna. When the multiple antenna is an RF antenna, it can be operated in monopolar or bipolar modes, and is capable of switching between the two. One or more sensors are positioned at an interior or exterior of the primary or secondary antennas to detect impedance or temperature. The feedback control system is coupled to each of the sensors and to the primary antenna which delivers RF, microwave, short wave energy and the like from the energy source to the secondary antennas while delivering electromagnetic energy to a targeted tissue mass. A cable connects the primary antenna to the energy source. One or more of the secondary antennas are electromagnetically coupled to the primary antenna to receive ablation energy from the primary antenna. Although the primary antenna is an antenna it need not have an ablation energy delivery surface. An insulation sleeve can be positioned around the primary and secondary antennas. Another sensor is positioned at the distal end of the insulation sleeve surrounding the primary antenna. The feedback control device can detect impedance or temperature at a sensor. In some embodiments, the feedback control system can include a multiplexer. Further, the feedback control system can provide an ablation energy output for a selected length of time, adjust ablation energy output and reduce or cut off the delivery of the ablation energy output to the antennas. The feedback control system can include a temperature detection circuit which provides a control signal representative of temperature or impedance detected at any of the sensors. Further, the multiple antenna device can be a multi-modality apparatus. One or all of the antennas can be hollow to receive an infusion medium from an infusion source and introduce the infusion medium into the targeted tissue mass.
Embodiments of the invention provide the advantage of being able to employ minimally invasive methods to rapidly obtain sufficient biopsy tissue samples to make accurate diagnosis of pulmonary disease while significantly reducing the risk of pneumothorax. Embodiments of the invention also provide the advantage of allowing the physician to obtain adequate biopsy tissue samples using an atraumatic device and method that reduces the risk of trauma including tears to pulmonary and pleural tissue, hemothorax and pulmonary hemorrhage and embolism. The invention further provides the advantage of an apparatus that prevents air from being accidentally sucked into the lung through the use of a control valve and can reliably seal perforated lung tissue at the biopsy site so as to prevent a pneumothorax or uncontrolled hemorrhage. Still further, the invention provides the advantage of using minimally invasive methods to treat a selected pulmonary tissue volume to achieve a desired treatment endpoint including complete ablation/necrosis of the selected tissue with minimal effect on surrounding tissue.